The home networking field has been increasing in popularity the last few years. The “digital home,” as referred to by industry insiders, will supposedly enable consumers to network and interface various types of appliances and devices throughout the home. For example, it is believed that the network will allow linking of such home appliances as alarm clocks, stereo equipment, televisions and kitchen appliances. For example, after an alarm clock has sounded and the network detects activity in the bathroom in the morning, then the network can alert the coffee maker in the kitchen to begin preparation of a pot of coffee. Or, the bathroom scale can be continually monitored and provide input data upon each weighing to exercise software on a home computer linked to home exercise equipment.
Manufacturers from a wide variety of industries have been developing “networked” products to meet this emerging market. Due to lack of industry standards, manufacturers have engaged in developing their own proprietary network protocols and hardware in order to connect devices. As a response to the network incompatibility issue, some industry groups have been formed in order to create “standards” so that manufacturers following these standards are able to create compatible devices adhering to a specific protocol in software and hardware.
Groups such as WI-FI, which adhere to the 802.11x IEEE standards, are producing products today to allow fast connection between computer and multi-media systems. This particular standard is designed for transferring a large amount of data across a wireless network. Other groups such as the “Powerlin” group have developed fast data transfer networks using the existing home electrical wiring. Yet other groups have formed standards such as HomeRF.
When fast data rates are required, the aforementioned standards work very well. However, in cases where simple control signals such as “on\off” and status are required, a fast data network becomes “overkill” for these simple applications. Manufacturers requiring a simpler type of network for control applications have developed standards such as “Zigbee” and “Z-wave” in an effort to keep their overall systems price competitive. These “control” networks add yet another level of complexity to the home integrator whose job is to make all of these systems work together seamlessly. In addition, different standards are being developed which presumably link the internet and cell phone communications systems with the home network. It is also believed that the home network may be extended into devices maintained in the garage or barriers that are accessible by an operator controlling the barrier, but the communication standards utilized by the garage door operator and the home network are not at all compatible. Since the goal of the home network is to connect all devices together and to offer consumers easy-to-use interfaces, it is necessary to develop interfaces capable of “bridging” devices utilizing incompatible communication protocols. One type of “power line” network utilizes the X-10 standard. This scheme uses existing infrastructure wiring to enable devices to communicate with one another. However, one of the most expensive components in a traditional wired network is the cost of the wire itself, and the cost of each point drop or node needed to access the wired network. Power line networking uses existing electrical wiring to create a network to serve both computers and other electronic devices. Since most locations have plenty of power outlets, the proponents of the X-10 standard suggest the technology will be easier and eventually less expensive to implement than other wired types of networking. Indeed, various home automation systems have been designed for the remote control of lights and appliances centered about the standard electrical wiring already in existence in a facility. Additionally, adapters from companies have been developed to use power lines to carry phone signals to rooms without phone jacks. Other products have been introduced to allow for digital data transfer over power lines for computers and internet devices.
There are two established methods that are used to send and receive data over existing power lines. The first is Orthogonal Frequency-Division Multiplexing (OFDM) with forward error-correction. This scheme is very similar to the technology found in DSL modems. OFDM is a variation of the frequency-division multiplexing (FDM) used in phone-line networking. FDM puts computer data on separate frequencies from the voice signals being carried by the phone line and separates the extra signal space into distinct data channels by splitting it into uniform chunks of bandwidth. In the case of OFDM, the available range of frequencies on the electrical subsystem (4.3 MHz to 20.9 MHz) is split into 84 separate carriers. OFDM sends packets of data simultaneously along several of the carrier frequencies allowing for increased speed and reliability. If electrical noise or a surge in power usage disrupts one of the frequencies, control circuitry used as part of the multiplexing system senses the change and switches that data to another carrier. This rate-adaptive design allows the control circuitry to maintain an Ethernet-class connection throughout the power-line network without losing valuable data.
The other method of sending and receiving data over a power line relies on frequency-shift keying (FSK) to send data back and forth over existing wiring. FSK uses two frequencies, one for the Is and another for the Os, to send digital information between the computers on the network. The frequencies used are in a narrow band just above the level where most line noise occurs. Although this method works, it has been found to be somewhat fragile. Anything that interferes on either frequency can disrupt the data flow and can cause the transmitting computer to have to resend the data and thus reduces the performance of the network.
One drawback of the power-line networks is that they are designed to work on 110-volt electrical systems and as such, the technology is not very useful in countries outside of North America that use different standards.
It is also known to use a radio frequency (RF) network so as to avoid the necessity of wires. Such a network allows for devices to access the network in the same way that one listens to a radio from almost anywhere. Radio frequency networks are also referred to as Wireless Local Area Networks (WLAN) which function by using electromagnetic waves to communicate between devices connected to the network. Such radio frequency networks are widely used in the United States and other countries and are advantageous inasmuch as they: permit mobility of the user; can be deployed where cabling would otherwise be very difficult; and are cost effective when compared to wired networks. Moreover, several established standards allow for interoperability of devices over radio frequency networks. Standards like IEEE 802.11, BlueTooth, and cellular networks are all established and widely adopted. There are also other emerging standards including IEEE 802.15.4, namely the ZigBee standard and other derivatives like Z-Wave which target both lower band width network requirements. These lower band widths require much less power and are ideally suited for battery-operated applications.
The aforementioned wired and wireless networks employ an event controller which has stored internally, knowledge of external devices, and knowledge of how to communicate with each external device. Simple examples of an event controller are TV remote controls or garage door opener transmitters. In both examples, the respective controller has knowledge of how to control the target device, that is, the television or the garage door. In more elaborate implementations, an event controller has stored knowledge of a plurality of external devices and is capable of communicating with the devices either independently or collectively. An example of a collective communication is when an ALL-ON or ALL-OFF command from an X-10 power line controller to all the power line modules collectively controls them either to the on or off position.
Although the network scenarios described above are effective in their stated purpose, it will be appreciated that the various scenarios are unable to communicate effectively with one another. Therefore, there is a need in the art to be able to integrate the power line and radio frequency networks by use of a bridging device which embodies both types of hardware and protocols needed to interface with each. Such a device would allow for the local control of either type of network device via a built-in interface that can be taught, configured and re-configured to communicate between both types of networks and their respective devices.